The present invention relates to an aperture card reader by which the images on microfilms mounted on aperture cards are projected on a screen on an enlarged scale.
Aperture cards are laterally elongated cards of a specified size having a microfilm mounted in an apertured center portion thereof, the microfilm bearing microcopied information of documents, drawings, etc. Aperture cards have already been dimensionally standardized. Since such aperture cards are useful for filing immense amounts of information, they have found wide use for filing purposes. Various aperture card readers have been developed and commercially provided for viewing the microcopy images on the aperture cards by enlarging them and projecting them on a screen. Many of these aperture card readers serving as viewers also include printers for printing microfilm images on copy paper on an enlarged scale. (Such an apparatus is also called a "reader-printer.")
It is desirable that aperture card readers be equipped with a mechanism by which aperture cards can be automatically fed to and delivered from a pair of presser plates for holding the card therebetween for the projection of the image so that a large number of aperture cards can be copied rapidly while being easily handled. Many readers are presently available which are provided with such a mechanism. They are easy to operate, adapted to copy a large number of aperture cards efficiently and are accepted as very desirable for the user. Notwithstanding these advantages, the product nevertheless invariably has a disadvantage causing the following inconvenience to the user. In fact, the drawback to be described below has been the cost of achieving the foregoing benefits.
An aperture card has an aperture with a minor to major side ratio of about 2:3 and is usually used in a horizontal position, namely with the major sides of the aperture positioned horizontally. When a microfilm is mounted on the aperture card, the information on the film will be oriented vertically or horizontally depending on whether the information is microcopied on the film in its horizontal or vertical position. This is established when attaching existing microfilms to aperture cards for filing. With the conventional aperture card readers described above, on the other hand, the presser plates for holding the aperture card are adapted to hold the card only in a specified position, while the mechanism for automatically feeding and delivering aperture cards is also designed to feed the card to the presser plates is only one direction, i.e. the direction in which the minor sides are oriented or the direction in which the major sides of the card are oriented. Accordingly when microfilm images are enlarged and projected on the screen of the conventional aperture card reader for viewing, the images will invariably be projected in one of two positions, oriented either vertically or horizontally. In the latter case, the user suffers the inconvenience that the enlarged images will be lying on their side, so to speak.